Electrochemical detection of small molecule induced Pseudomonas aeruginosa biofilm dispersion

Abstract

A simple electrochemical assay to monitor the dispersion of Pseudomonas aeruginosa PA01 biofilm is described. Pyrolytic graphite (PG) electrodes were modified with P. aeruginosa PA01 using layer-by-layer (LbL) methods. The presence of the bacteria on the electrodes was directly monitored using square wave voltammetry (SWV) via the electrochemical reduction of electroactive phenazine compounds expressed by the bacteria, which indicate the presence of biofilm. Upon treatment of bacteria-modified electrodes with a 2-aminoimidazole (2-AI) derivative with known Pseudomonas anti-biofilm properties, the bacteria-related electrochemical reduction peaks decreased in a concentration dependent manner, indicating dispersal of the biofilm on the electrode surface. A similar 2-AI compound with negligible anti-biofilm activity was used as a comparative control and produced muted electrochemical results. Electrochemical responses mirrored previously established bioassay-derived half maximal inhibition concentration (IC50) and half maximal effective concentration (EC50) values.. Biofilm dispersal detection via the electrochemical response was validated by monitoring crystal violet absorbance after its release from electrode confined P. aeruginosa biofilm. Mass spectrometry data showing multiple redox active phenazine compounds are presented to provide insight into the surface reaction complexity. Overall, we present a very simple assay to monitor the anti-biofilm activity of compounds of interest.

Detection and Characterization of Bacterial Biofilms and Biofilm-Based Sensors

“…The impedimetric sensing principle serves the foundation of the so-called impedance microbiology (IM), where the change in the impedance between two electrodes that are exposed to the bacteria is used to identify the presence of microorganisms. This approach has allowed researchers to detect bacterial growth in real time by measuring the variations in the conductance, impedance, or capacitance of the bacterial solution. ,− ,− Briefly, the bacteria and the extracellular components of the biofilm are dielectric species which affect the overall impedance of the system. Therefore, by monitoring the impedance in the solution over time, the biofilm formation and the subsequent change in the composition and metabolism of the biofilm can be inferred …”

Combining hyperspectral imaging and electrochemical sensing for detection of Pseudomonas aeruginosa through pyocyanin production

“…7 Pyocyanin is ubiquitously produced by P. aeruginosa and one of its main virulence factors, characteristically produced by this bacterial species in a biofilm phenotype, its most efficient survival strategy. 27,[29][30][31] As a well-characterised compound across the electrochemical literature, pyocyanin has led to a wide range of sensing strategies through amperometric, voltammetric, or impedance-based detection. 20,29,30,32 Hyperspectral imaging (HSI) is a photographic imaging technique that captures detailed spectral information for each pixel of an image.…”

“…27,[29][30][31] As a well-characterised compound across the electrochemical literature, pyocyanin has led to a wide range of sensing strategies through amperometric, voltammetric, or impedance-based detection. 20,29,30,32 Hyperspectral imaging (HSI) is a photographic imaging technique that captures detailed spectral information for each pixel of an image. The resulting hyperspectral datacube can be thought of as a collection of greyscale images corresponding to narrow bands of the electromagnetic spectrum.…”

“…27,29–31 As a well-characterised compound across the electrochemical literature, pyocyanin has led to a wide range of sensing strategies through amperometric, voltammetric, or impedance-based detection. 20,29,30,32…”

Further understanding of Pseudomonas aeruginosa’s ability to horizontally acquire virulence: possible intervention strategies

“…Innovations in electrochemical engineering may also provide one avenue for researchers to find new dispersins. In 2018, Robb demonstrated the use of pyrolytic graphite electrodes to assess potential dispersal-inducing properties of 2-aminoimidazole (2-AI) [78]. Such analytical technologies may enable microbiologists to better understand and measure the dispersal potential of novel antimicrobial and anti-biofilm molecules.…”